Toward a General Formulation of Dispersion Effects for Solvation Continuum Models

Area of Science:

• Computational chemistry
• Quantum mechanics
• Physical chemistry

Background:

• Continuum models are essential for solvation free energy calculations.
• The Amovilli and Mennucci quantum model provides a basis for solvation studies.
• Incorporating dispersion forces is critical for accurate quantum chemical calculations.

Purpose of the Study:

• To revise the Amovilli and Mennucci quantum model by incorporating dispersion contributions.
• To develop a generalized formulation applicable to various quantum mechanical methods.
• To investigate the impact of dispersion on vertical excitation energies using time-dependent DFT.

Main Methods:

• Revision of the Amovilli and Mennucci quantum model.
• Implementation of a single adjustable solvent-dependent parameter.
• Application of Density Functional Theory (DFT) and time-dependent DFT (TD-DFT).

Main Results:

• The revised model successfully includes dispersion contributions to solvation free energy.
• Dispersion effects are a significant factor in absolute solvent effects.
• A cancellation effect is observed when considering relative solvent-solute shifts.

Conclusions:

• The generalized quantum model offers improved accuracy for solvation free energy calculations.
• Dispersion effects play a complex role, significantly influencing absolute solvation but showing cancellation in relative shifts.
• The model's adaptability to different quantum mechanical descriptions enhances its utility in computational chemistry.